1. Field of the Invention
The present invention relates to the field of telecommunications. More particularly, the present invention relates to a system and a method for digital modulation and demodulation using FFT-based multitone concepts.
2. Description of the Related Art
Intersymbol interference distorts the signal content of a transmitted signal, possibly resulting in severe information transmission errors. Intersymbol interference arises from channel distortion, multipath spread, and/or sampling offset, and places significant design constraints on transmitting and receiving filters. The effects of intersymbol interference increase with increasing transmission speed and, consequently, cause a major impediment for broadband high-speed transmission, especially for wireless multimedia in which multipath signal components are frequently produced.
Multipath components are combined in a Code Division Multiple Access (CDMA) rake receiver used for wireless communications, but frequently the spread of the multipath components is comparable to, or larger than, the symbol interval, thus giving rise to substantial intersymbol interference. Another conventional approach for minimizing intersymbol interference is by using sophisticated channel equalization techniques.
What is needed is a way to avoid intersymbol interference without using channel equalization in high-speed broadband networks.